What command is used to count just the number of lines contained in a file?

The correct answer is D. wc - l.

The wc command is used to count the number of lines, words, and characters in a file. The -l option tells wc to only count the number of lines.

The other options are as follows:

• -r: Count the number of lines that are not blank.
• -w: Count the number of words.
• -c: Count the number of characters.

I hope this helps! Let me know if you have any other questions.